How to do lengthy processing in an element

[filnet]

Hi,

I have an element that needs, at some point in time after analyzing a number of frames, to do a lengthy processing. Currently it is done in the chain() method, stalling the pipeline, but could be done asynchronously.

Does gstreamer have facilities for launching some task in a separate thread and make the result available to the element once done, all this without having to muck with threads, locks, etc... ?

Cheers,

Philippe.

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[filnet]

Answering my own question : gst_element_async_call() seems to fit the bill.

Le Vendredi 2 décembre 2016 17h30, philippe renon <[hidden email]> a écrit :

Hi,

I have an element that needs, at some point in time after analyzing a number of frames, to do a lengthy processing. Currently it is done in the chain() method, stalling the pipeline, but could be done asynchronously.

Does gstreamer have facilities for launching some task in a separate thread and make the result available to the element once done, all this without having to muck with threads, locks, etc... ?

Cheers,

Philippe.

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[Sebastian Dröge-3]

On Fri, 2016-12-09 at 09:50 +0000, philippe renon wrote:
> Answering my own question : gst_element_async_call() seems to fit the
> bill.

That's more for one-shot, simple tasks that don't take are not
continuously running. Like if you have to do some action on your
element from a non-streaming thread.

For long-running tasks that are just the element processing, you should
consider starting a new thread.

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[filnet]

It is a one shot task that I need to execute.

The element analyzes video frames and once it has accumulated enough samples it needs to do a one shot computation that can take several seconds to complete.

The result of the computation needs to be fed back into the element.

Le Vendredi 9 décembre 2016 10h57, Sebastian Dröge <[hidden email]> a écrit :

On Fri, 2016-12-09 at 09:50 +0000, philippe renon wrote:

> Answering my own question : gst_element_async_call() seems to fit the
> bill.

That's more for one-shot, simple tasks that don't take are not
continuously running. Like if you have to do some action on your
element from a non-streaming thread.

For long-running tasks that are just the element processing, you should
consider starting a new thread.

--
Sebastian Dröge, Centricular Ltd · http://www.centricular.com

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[Sebastian Dröge-3]

On Fri, 2016-12-09 at 10:05 +0000, philippe renon wrote:
> It is a one shot task that I need to execute.
>
> The element analyzes video frames and once it has accumulated enough
> samples it needs to do a one shot computation that can take several
> seconds to complete.
> The result of the computation needs to be fed back into the element.

Does the element have to wait until that computation is finished before
it can do anything else?

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[filnet]

> Does the element have to wait until that computation is finished before
> it can do anything else?

No, it does not.

Le Vendredi 9 décembre 2016 11h09, Sebastian Dröge <[hidden email]> a écrit :

On Fri, 2016-12-09 at 10:05 +0000, philippe renon wrote:
> It is a one shot task that I need to execute.
>
> The element analyzes video frames and once it has accumulated enough
> samples it needs to do a one shot computation that can take several
> seconds to complete.
> The result of the computation needs to be fed back into the element.

Does the element have to wait until that computation is finished before
it can do anything else?

--
Sebastian Dröge, Centricular Ltd · http://www.centricular.com

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[Sebastian Dröge-3]

On Fri, 2016-12-09 at 10:11 +0000, philippe renon wrote:
>
> > Does the element have to wait until that computation is finished
> before
> > it can do anything else?
> No, it does not.

Then this sounds like the right API :)

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Sebastian Dröge, Centricular Ltd · http://www.centricular.com
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